JPS63297230A - Molding mold for glass moldings - Google Patents

Abstract

PURPOSE:To obtain glass moldings having high precision and requiring no polishing after press molding, by providing a surface layer consisting of Pt and Ni or Cr through an intermediate layer consisting of glass on a substrate. CONSTITUTION:The molding mold is equipped with a substrate, intermediate layer provided on the substrate and surface layer provided on the intermediate layer and the intermediate layer is composed of at least one kind of glass. The surface is further composed of at least two kind of metals containing 50-95wt.% Pt and 5-40wt.% Ni and/or Cr. It is required for the glass used as an intermediate layer material that the coefficient of thermal expansion is value between that of the substrate and that of the surface layer. The intermediate layer may be single layer or plural layers and in the case of the latter layer, when the coefficient of thermal expansion of the glass in the each layer is successively increased from the substrate side toward the surface layer side, adhesion between the substrate and surface layer is further improved, compared with the case of the single layer.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mold for press-molding glass;
In particular, the present invention relates to a mold for obtaining a high-precision glass molded body that does not require polishing after press molding.

[Prior Art] As a mold for obtaining a glass molded body by press molding, a mold using silicone carbide or silicon nitride (see Japanese Patent Laid-Open No. 45613/1983) is known. Recently, a coating film of a negative metal alloy made of platinum and other noble metal elements is formed as a surface layer on a substrate mainly composed of tungsten carbide (see Japanese Patent Application Laid-Open No. 60-246230), and a substrate made of silicon. A coating film of a noble metal alloy consisting of platinum and other negative metal elements is formed as a surface layer (both 61-
242922) has been proposed.

[Problems to be Solved by the Invention] However, silicon nitride and silicon carbide disclosed as materials for molds in JP-A-52-45613 are very hard materials, and cannot be finished into an aspherical shape. When performing this process, cutting using a diamond cutting tool is not possible, making high-precision machining extremely difficult.Also, the extreme surface layer of these materials tends to become an oxidized layer, so it is easy to fuse with the glass during press molding. There were drawbacks.

In addition, in the mold disclosed in JP-A No. 60-246230, in which a platinum-based negative metal alloy layer is formed as a surface layer on a tungsten carbide base, tungsten carbide has a higher precision than the above-mentioned silicon nitride or silicon carbide. Although it has the advantage of being somewhat easy to process, it is still not sufficient, and furthermore, by forming optical glass at high temperatures for a long time, the base material tungsten carbide is oxidized and the area density decreases, resulting in negative There were disadvantages in that the metal alloy layer was easily peeled off, and the molding properties of the glass molded body during molding were also poor.

Furthermore, silicon disclosed as a base material in JP-A No. 61-242922 has the advantage that it can be precisely processed by cutting, but according to experiments by the present inventors, The platinum-based noble metal alloy film has poor adhesion to silicon and the thermal expansion coefficients between the two are greatly different, so the negative metal alloy film easily peels off from the silicon substrate after several press moldings, and It has been found that a surface layer made of only a combination of platinum and noble metals such as iridium, osmium, rhodium, palladium, and ruthenium does not have very good mold release properties of the glass molded body during press molding.

Therefore, an object of the present invention is to solve the above-mentioned drawbacks of the conventional molds, and to provide a glass that simultaneously satisfies all of precision workability by cutting, adhesion of the surface layer to the base, and mold releasability of the glass molded product. The object of the present invention is to provide a mold for a molded article.

[Means for Solving the Problems] The present invention has been made to achieve the above object, and the mold for a glass molded article of the present invention comprises a base, an intermediate layer provided on the base, , a surface layer provided on the intermediate layer, the intermediate layer comprising at least one glass, and the surface layer comprising 50-95 wt% platinum, 5-40 wt% nickel and/or or chromium.

The present invention will be explained in detail below.

The mold for a glass molded article of the present invention includes a base, an intermediate layer provided on the base, and a surface layer provided on the intermediate layer.

First, to explain the base material, the base material is not particularly limited as long as it satisfies the hardness, strength, heat resistance, etc. generally required for a base, and examples include silicon carbide, silicon nitride, tungsten carbide, cermet, and stainless steel. , silicon, etc. can be used.

Among the above-mentioned base materials, when hard materials such as silicon carbide, silicon nitride, and tungsten carbide are used, after processing into a shape close to the final shape of the mold, an intermediate layer and a surface layer are sequentially formed. After that, it is preferable to perform high-precision cutting using a diamond cutting tool to obtain the final aspherical shape.

Further, when the base material is a soft material such as silicon, it is preferable to cut the silicon itself with high precision using a diamond cutting tool.

In the mold of the present invention, an intermediate layer is provided on the above-mentioned base, and the intermediate layer is made of at least one type of glass.

The intermediate layer prevents the base from oxidizing, prevents the metal components in the base from diffusing into the surface layer, prevents the base and the surface layer from peeling off due to the difference in thermal expansion coefficient, and improves the adhesion between the two. The glass used as the intermediate layer material in the present invention can satisfactorily achieve these objectives. This is because glass has the following properties and characteristics.

(il) Glass can form a uniform coating film on the substrate, which prevents the substrate from oxidizing.It also acts as a barrier layer between the substrate and the surface layer, separating the two, and the surface layer of the components in the substrate. prevent the spread to.

(iii) Glass has good affinity with both the substrate and the platinum alloy surface layer, and by changing the types and composition ratios of the glass components, the coefficient of thermal expansion can be adjusted to be between the coefficient of thermal expansion of the substrate and that of the surface layer. Since it can be arbitrarily set to a desired value, strong adhesion can be formed between the base material and the platinum alloy surface layer material even if they are varied over a wide range.

As mentioned above, the glass used as the intermediate layer material must have a coefficient of thermal expansion between the coefficient of thermal expansion of the base layer and the coefficient of thermal expansion of the surface layer (3.5X10' to 10.5X10'/'C). However, it is also necessary that the glass layer does not soften at the pressing temperature (the temperature at which the viscosity of the glass to be formed is approximately 108 to 1010 poise), that is, the glass transition temperature (Tq) of the glass layer is higher than the pressing temperature. be. Examples of such glasses include 27-55 wt% silicon oxide, 10-24 wt% boron oxide, and 2-12 wt% aluminum oxide.
glass consisting of 1 to 6 wt% of silicon oxide, 17 to 4 Qwt% of boron oxide, 20 to 57 wt% of lanthanum oxide and 50 to 57 wt% of silicon oxide; 65
wt%, aluminum oxide 8-20wt%, zinc oxide 1
-16w[%], glass consisting of 1-16wt% of magnesium oxide and other components.

The intermediate layer may be a single layer or multiple layers; in the latter case, if the coefficient of thermal expansion of the glass in each layer is increased sequentially from the base side to the surface layer side, the intermediate layer may be a single layer. Compared to the case where it consists of layers, the difference in thermal expansion coefficient between the base and the intermediate layer and between the intermediate layer and the surface layer can be kept low.
Adhesion between the base and surface layer is further improved. Note that the thickness of the intermediate layer is suitably about 0.03 to 10 μm. 0.03
If it is less than μm, a uniform layer cannot be formed, and if it is less than 1
This is because there is no advantage to increasing the thickness even if it exceeds 0 μm.

The glass intermediate layer is formed by means such as sputtering.

In the mold of the present invention, a surface layer is provided on the above-mentioned intermediate layer, and the surface layer contains 50 to 95 wt% of platinum and 5 to 4 wt% of platinum.
It is composed of at least two kinds of metals including 0111t% of nickel and/or chromium.

The present inventors discovered that with conventional surface layers made of platinum and precious metal alloys such as iridium, the mold release properties of glass molded bodies during press molding were not very good. It has been found that when a surface layer of a metal containing at least 2fa of nickel and/or chromium is used as the surface layer, the mold releasability is significantly improved. The platinum content was limited to 50 to 95 wt% and the nickel and/or chromium content was limited to 5 to 40 wt% because platinum was 95 wt%.
t%, so that nickel and/or chromium exceeds 5w
If the platinum content is less than 5Qwt%, the hardness will be low and scratches will easily occur, and the mold release property of the glass during press molding will not be good.On the other hand, if the platinum content is less than 5Qwt%, nickel and Alternatively, if chromium exceeds 4Qwt%, nickel and/or chromium will easily diffuse into the glass molded body during press molding.

Addition of rhodium, iridium, palladium, gold, etc. in addition to the above-mentioned platinum, nickel and/or chromium makes it possible to withstand even higher temperature press molding.

The surface layer is preferably formed by sputtering or the like.

When using a material such as silicon nitride, silicon carbide, or tungsten carbide as the base material, which is difficult to cut into a highly accurate aspherical surface using a diamond cutting tool, the thickness of the surface layer should be determined by Since it is necessary to perform accurate aspherical cutting, it is preferable to use a thickness of 3 to 50 μm, but if silicon is used as the base material, as it is relatively easy to perform long-time aspherical cutting using a diamond cutting tool. For this purpose, a thickness of 0.03 to 10 μm is sufficient.

In addition, when the final shape is a spherical surface, the base material may be mirror-finished, the intermediate layer and the surface layer may be sequentially coated, and this may be used as the final surface. In this case, the total coating thickness of the intermediate layer and surface layer is preferably 10 uI or less.

[Examples] Hereinafter, the present invention will be further explained with reference to Examples, but the present invention is not limited to these Examples.

FIG. 2 is a cross-sectional view showing the structure of a press molding machine that accommodates an example mold. The mold is composed of an upper mold 1, a lower mold 2, and a guide mold 3. The upper mold 1 and the lower mold 2 are slidably housed in the guide mold 3, and the upper mold 1 and the lower mold 2 are A glass gob 4 to be formed is set between them. In this embodiment, the guide mold 3 is made of silicon carbide, has an outer diameter of 26 mrn, and an inner diameter of 1 mrn.
A 4 m 1 piece with a height of 40 mm was used as it was without providing an intermediate layer or a surface layer. The upper mold 1 and the lower mold 2 have an outer diameter of 14+m and a height of about 20s+, and are made of tungsten carbide and silicon carbide.One end surface is finely ground into a concave shape, and this is used as the base. . On the other hand, the five types of glass compositions shown in Table 1■
~■ were prepared and used as targets for forming the intermediate layer. 1st
On the front is the heat of the glass for the intermediate layer! The tensile modulus and transition temperature are also given. Table 2 collectively shows the type of substrate used in this example, the type and thickness of the glass of each intermediate layer, and the composition and thickness of the surface layer. For example, to explain in detail the fabrication example of the mold of Experimental Example 4 shown in Table 2, tungsten carbide containing about 6% cobalt as a binder, which was densified by -11P treatment during sintering, was thermally expanded. Coefficient 5. OXl 0"6/'C> was processed with a diamond grinding wheel into an aspherical shape close to the final shape as shown in Fig. 1, and this was used as the substrate 5. Prior to forming a film using a sputtering device, the surface was polished by reverse sputtering. Clean the glass ■ shown in Table 1 (thermal expansion coefficient 6.5x
10'/''C) as a target, and predetermined film forming conditions (argon gas pressure I x 10' torr, film forming rate 0.
05 μm/min) to form the first intermediate layer 6.
(thickness 0.5 μm), glass ■ (coefficient of thermal expansion 7.9
×10-6/'C) under the same conditions as the target.
To form the width layer 7, a film thickness of 0.5 μl (1 l) was formed, and finally a film was formed under almost the same conditions using a platinum (70 wt%)-nickel (30 wt%) alloy (thermal expansion coefficient: 11 x 10-6/°C) as a target. A surface layer 8 having a thickness of 10 μl was formed. next,! Using an 11-crystal diamond cutting tool, approximately 5 μm from the surface was cut to complete an aspherical mold. At this time, the surface roughness was 10,000 AR. Although ax is also deposited on the side surface of the mold in FIG. 1, the film may be deposited only on the molding surface of the mold.

In Experimental Example 6, the base was processed into a spherical surface, and the surface layer was 50 μm.
This is an example in which the surface layer was sputtered to a thickness of m and then processed into an aspherical surface. In addition, in Experimental Example 1, the substrate was mirror-finished into a highly accurate spherical surface, and after forming an intermediate layer of 2 μm, a surface layer of 1 μm was formed.
A film was formed and completed as a spherical type, and the surface roughness at this time was 80AR. Similarly, in Experimental Examples 2.3 and ax 5, molds of the present invention having tungsten carbide as the base were obtained.

Experimental Examples 7 to 9 were based on a silicon carbide sintered body coated with silicon carbide using the CVD method, and after mirror-finishing this into a spherical surface, the intermediate layer and surface layer were sputtered to complete the spherical mold. The surface roughness at this time was 30AR. In Experimental Examples 10 to 15, the silicon force aX-bite sintered body was processed with a grindstone in advance into an aspherical shape close to the final shape, the intermediate layer and the surface layer were formed by sputtering, and then the surface layer was made into the final aspherical shape. It is processed and finished.

Next, an example of press molding using the mold thus produced will be described with reference to FIG. 2.

First, in a mold of the present invention consisting of an upper mold 1, a lower mold 2, and a guide mold 3, a glass composition of SiO227,8, with a glass composition of wt%,
Na O1,8, K, 01.2', Pb0 65.
2, A evening 2032.0. A spherical to-be-molded glass lump 4 of optical glass (transition temperature 435° C.) made of Ti022.0 (transition temperature 435° C.) and having a diameter of 10 m is placed on a support ring via a support stand 10, and in an N2 atmosphere, a quartz tube 11 is placed. A heater 12 wrapped around the outer periphery of the glass block 4 to be formed together with the mold
is heated, the pushpiece 13 is lowered, and the temperature is increased to 500°C and 80°C.
It was pressed for 30 seconds at a pressure of Kg/crR2. Thereafter, the pressure is released, and the press-molded glass molded body is slowly cooled to the above transition temperature while in contact with the upper mold 1 and the lower mold 2, and then rapidly cooled to around room temperature, and the glass molded body is transferred to the mold. I took it out.

As a result of repeating press molding 1,000 times using the molds of Experimental Examples 1 to 15, in all experimental examples, the glass molded product had good mold releasability and a chemical reaction occurred at the contact surface with the mold. No appearance was observed, and the surface roughness was 10.
The aX was below 0AR, and the transparency was also good. In addition, no peeling of the surface layer or intermediate layer occurred in any of the molds, and the surface roughness and mirror finish were maintained. The above effect was particularly remarkable in Experimental Examples 4 to 6 and Experimental Examples 10 to 15, in which the glass intermediate layer was composed of multiple layers.

On the other hand, in the mold of Experimental Examples 1 and 11 and Comparative Experimental Example 1C, which had the same surface layer but no intermediate layer, cobalt, which is a binder for the tungsten carbide base, diffused and reached the surface. My skin became noticeably rough.

In addition, the molds of Comparative Experiment Examples 2C and 9C, which had the same 313 and surface layer as Experiment Examples 2 and 9, but did not have an intermediate layer, had no intermediate layer, so both had 10
The surface layer developed 111 after press molding ~20 times.

Although not shown in Table 2, tungsten carbide is sputtered with silicon carbide to a thickness of 0.3 μm, and then the surface layer of the present invention is sputtered to a thickness of 2 μm without providing an intermediate layer. The surface layer peeled off.

Furthermore, although this is also not shown in Table 2, a surface layer consisting of a coating film of each alloy of platinum-rhodium and platinum-iridium, which is not included in the surface layer material of the present invention, is coated through the intermediate layer of the present invention. When press molding was carried out in the same manner using the respective molds, the releasability of the glass molded product was poor from the first press molding.

In addition, although the surface layer of the mold was slightly oxidized in the above-mentioned experimental example, it was found that this did not affect the mold releasability or surface roughness of the glass molded product during press molding.

Example ■ Similar to Example ■, the guide mold 3 was made of silicon carbide and had the same shape. However, unlike Example ■, silicon was used as the material for the upper mold 1 and the lower mold 2, and this was processed. An upper mold 1 and a lower mold 2 having an outer diameter of 14 # and a height of approximately 20 m were made, and one end surface was precisely cut into a concave aspherical shape using a single crystal diamond cutting tool. Here, a silicon single crystal with an axial direction of <111> was used as the silicon, but this is not necessarily necessary. On the other hand, 3 shown in Table 1
Glasses (1), (2), and (2) having different compositions were prepared and used as Targetera 1 for forming an intermediate layer. Table 1 also shows the thermal expansion coefficient and transition temperature of the glass for the intermediate layer. Table 3 collectively shows the type and thickness of the glass used for each intermediate layer in this example, the composition of the surface layer, and the film θ. For example, experimental example 2
To explain in detail the manufacturing example of mold No. 8, as shown in Fig. 1, on a base 15 of silicon (coefficient of thermal expansion 4.2xlO-6/°C) which has been precisely cut into an aspherical shape,
Before forming a film using a sputtering device, the surface is cleaned by reverse sputtering, and the glass shown in Table 1 (thermal expansion coefficient 6.3X'10'/°C) is targeted, and the specified film forming conditions (argon Gas pressure 1 x 10-
3 torr and a film formation rate of 110.05 μm/min to form the first intermediate layer 6 (thickness: 0.3 μm), and on top of that, a second intermediate layer 6 was formed under the same conditions using glass (coefficient of thermal expansion fi7.9×10'/°C) as a target. 2 to form an intermediate layer 7 with a film thickness of 0.3
μll1), @after platinum (70wt%)-nickel (1
5wt%) - Chromium (15wt%) alloy (thermal expansion coefficient 9
．． A surface layer 8 having a thickness of 0.3 μm was formed under almost the same conditions using a 6×10 −6 layer (° C.) as a target. The surface roughness at this time was 100AR48x. Films were formed using almost the same method for other experimental examples.

In the mold thus prepared, the glass composition was wt.
%rsio 27.8, Na2O1,8, K O1
,2,PbO65,2,Al2O32,O,T i 0
22,0 A spherical glass lump 4 with a diameter of 10 mm made of Teal Optical Glass (transition temperature 435°C) was placed on a support rod 9 via a support stand 10 in a molding manner whose main part is shown in FIG. The glass lump 4 to be formed is heated together with the mold by the heater 12 wound around the outer periphery of the quartz tube 11 in an N2 atmosphere, and the push rod 13 is lowered to produce 80 kg/ctn 2 at 500°C. It was pressed for 30 seconds at a pressure of Thereafter, the pressure is released, and the press-molded body is slowly cooled to the above transition temperature while in contact with the upper mold 1 and the lower mold 2, and then rapidly cooled to around room temperature, and the glass molded body is removed from the mold. I took it out.

Using the molds of Experimental Examples 21 to 34, each
As a result of repeating the press molding process, in all experimental examples, the glass molded product had good mold releasability, no chemical reaction was observed on the contact surface with the mold, and the surface roughness was 1.
00ARIIlax or less, and the transparency was also good. In addition, no peeling of the surface layer or intermediate layer occurred in any of the molds, and the surface precision and mirror surface state were maintained. These effects were particularly remarkable in Experimental Examples 27 to 34 in which the glass intermediate layer consisted of two layers.

On the other hand, in the mold of Comparative Experimental Example 28C, which had the same base and surface layer as Experimental Example 28 but did not include an intermediate layer, the surface layer peeled off after several press moldings. Although not shown in Table 3, platinum-rhodium and platinum-iridium alloys that are not included in the surface layer of the present invention may be formed as a surface layer through the same two-layer intermediate layer as in Experimental Example 28. When press molding was performed in the same manner using a molded article on which a coating film was formed, the mold release properties of the glass molded article were poor from the first press molding.

Note that the silicon used as the base material in this example is a material that is relatively easily oxidized, and may already be slightly oxidized before sputtering, but there is no problem with coating such a base. Alternatively, it may be slightly oxidized before coating.

In addition, in the above-mentioned Examples (■) and (■), the glass to be formed was S i 0 with a pressing temperature of around 540°C.
2-8203-L, 120-CaO-1a OT i
Although OZr ONb2O5 glass having a transition temperature of 600° C. or higher was used as the glass for the intermediate layer, the glass to be formed and the glass for the intermediate layer are not limited to these. The pressing temperature of the glass to be formed, that is, the temperature at which the glass viscosity becomes approximately 108-1010 poise, is preferably 650°C or less. Further, as the glass for the intermediate layer, a glass whose transition temperature is higher than the pressing temperature of the glass to be formed may be selected. For example, if the glass to be formed is a low softening point glass with a pressing temperature of about 400° C., the selection range of the glass for the intermediate layer is very wide.

[Effect of Bonmei] According to the present invention, by providing a surface layer mainly composed of platinum, nickel, and/or chromium, the mold releasability of the glass molded body during press molding becomes very good, and
By providing a glass layer as an intermediate layer between the base and the surface layer, adhesion is improved so that peeling of the film does not occur, and oxidation of the base is also prevented, resulting in a mold with a long life.

In addition, when silicon is used as the base material, high-precision aspherical cutting becomes easy, and even when base materials other than silicon, such as dungesten carbide and silicon carbide, are used, after forming a surface layer. This has the advantage of facilitating high-precision machining of the mold surface, especially aspherical surface machining.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a mold according to the present invention showing the structure of a base, an intermediate layer, and a surface layer, and FIG. 2 is a cross-sectional view showing the structure of a press molding machine housing the mold according to the present invention. 1... Upper mold, 2... Lower mold, 3... Guide mold, 4...
・Glass lump to be formed, 5... Base, 6... First intermediate layer, 7... Second intermediate layer, 8... Surface layer, 9... Support rod, 10... Support stand , 11...quartz tube, 12...
Heater, 13... Push rod, 14... Heat lightning pair.

Claims (4)

[Claims] (1) comprising a base, an intermediate layer provided on the base, and a surface layer provided on the intermediate layer, the intermediate layer comprising at least one type of glass, and the surface layer 1. A mold for a glass molded article, characterized in that the mold is made of at least two metals containing 50 to 95 wt% of platinum and 5 to 40 wt% of nickel and/or chromium. (2) The intermediate layer is composed of multiple layers, and the coefficient of thermal expansion of the glass of each layer constituting the multiple layers is between the coefficient of thermal expansion of the base and the coefficient of thermal expansion of the surface layer, and the surface layer 2. The mold according to claim 1, wherein the number of molds increases gradually from side to side. (3) The mold of claim 1, wherein said substrate is selected from the group consisting of tungsten carbide, silicon carbide, silicon nitride, cermet, stainless steel, and silicon. (4) The molding according to claim 1, wherein the surface layer further contains at least one metal selected from the group consisting of rhodium, iridium, palladium, and gold in addition to platinum, nickel, and/or chromium. Type.